Activity patterns of birds in the central Free State, South Africa

[摘要] Activity patterns of bird species were studied at Glen Agricultural College within the grasslandarea of the central Free State, South Africa, during a period of 11 years (July 1997 - July2008). The study focused on a specific grassland locality where 5-minute checklists were compiledcontinuously from dawn to dusk at least once a week for a total of 656 days. Data were alsocollected each minute for selected species. Additional observations in an adjacent tree and shrubdominated drainage line included I-minute checklists compiled during transects over a two-yearperiod (late autumn 2000/1 to mid-autumn 2002/3) as well as surveys from a fixed positionfrom dawn to approximately 70 minutes after sunrise during 2007/8. The central aim of thestudy was to quantify and explain annual, seasonal and daily activity patterns of all bird speciesrecorded in the study area. This data is summarised in separate species accounts where aspectsof the annual cycle, particularly breeding and moulting, were also considered. In addition, thepotential influence of rainfall was investigated.The study reveals, for the first time, how the activity patterns of a southern African birdcommunity change through time, and how the amount and timing of rainfall can influence thesepatterns. In spite of similarities amongst species when daily, seasonal and annual patternsare considered separately, the study also shows that each species is unique when all its datais considered simultaneously. Because activity patterns can have a substantial influence onthe detectability of a species, the accuracy and usefulness of surveys aimed at estimating birdnumbers is consequently questioned. The study at Glen also shows how activity patterns can beused to help unravel the annual cycle of species in a time and cost effective way.

[发布机构] University of the Free State